Lock Hopper Transfer for Olefin Polymerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multistage olefin polymerization processes face challenges in continuously and reliably transferring polymers from upstream slurry reactors to downstream gas-phase reactors without altering the gas composition, leading to discontinuous operations and potential polymer quality issues.
Innovation Solution
A process involving heating the polyolefin slurry to evaporate the liquid medium, separating the polymer particles, and using a couple of lock hoppers working intermittently in parallel to transfer the particles, where one hopper is continuously filled and the other is pressurized with gas from the downstream reactor, ensuring a continuous and reliable transfer without significant monomer carryover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer is transferred from upstream slurry reactor to downstream gas-phase reactor using conventional methods, then polymer transfer is achieved, but the gas composition in the downstream reactor is altered and monomer carryover occurs
Solution Approach 1:
The transfer system is segmented into multiple functional sections: a heating section with heating elements to evaporate liquid medium, a separation section to separate polymer particles from vapor, and a transfer section using lock hoppers. This segmentation allows each section to perform its specific function efficiently while preventing monomer carryover to the downstream reactor.
Solution Approach 2:
The polymer slurry undergoes preliminary heating and evaporation of the liquid medium before transfer to the downstream reactor. This preliminary action removes the harmful liquid phase and associated monomers, ensuring that only dry polymer particles enter the gas-phase reactor, thus maintaining gas composition stability.
2Productivity
If polymer slurry is heated to evaporate liquid medium, then continuous transfer is enabled, but energy consumption increases
Solution Approach 1:
The system employs feedback control through temperature sensors and controllers that monitor the heating process and adjust energy input accordingly. This ensures optimal heating efficiency and prevents excessive energy consumption while maintaining continuous polymer transfer.
3Reliability
If lock hoppers are used for polymer transfer, then continuous transfer without monomer carryover is achieved, but device complexity increases
Solution Approach 1:
The lock hoppers are designed to perform multiple functions: they serve as transfer vessels, pressure equalization chambers, and monomer removal devices. This multi-functionality reduces the need for separate components, thereby managing device complexity while ensuring reliable continuous transfer operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for a continuous and reliable transfer of polymers, maintaining the gas composition in the downstream reactor and preventing undesired monomer entry, thus optimizing polymerization conditions and product quality.
Implementation Method 1
heating the slurry of polyolefin discharged from the upstream reactor to evaporate the liquid polymerization medium
Implementation Method 2
separating the polyolefin particles from the evaporated phase in at least one separation chamber
Data Source
Figure 1
AI summary
A process for the multistage polymerization of olefins in a sequence of an upstream slurry reactor and a downstream gas-phase reactor, the transfer of polymer from the upstream reactor to the downstream reactor comprising the following steps: a) heating the slurry of polyolefin particles to evaporate the liquid polymerization medium; b) separating the polyolefin particles from the obtained gaseous phase in at least a separation chamber; c) transferring the polyolefin particles to said downstream reactor by means of a couple of lock hoppers working intermittently in parallel, where one of said lock hoppers is continuously filled with the polymer coming from said separation chamber, while simultaneously the other one is continuously pressurized by means of a gas comprising the reaction mixture coming from said downstream reactor.